I have a friend who is always trying to convert me to his religion. I am not really interested in his religion and I have told him so but he won't leave me alone. What can I do?

The first thing you must understand is that this person is not really your friend. A true friend accepts you as you are and respects your wishes. I suspect that this person is merely pretending to be your friend so he can convert you. When people are trying to impose their will on you they are certainly not friends.